#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
#define rep(i, a, b) for (int i = (a); i <= (b); i++)
#define per(i, a, b) for (int i = (a); i >= (b); i--)
#define endl '\n'
const int N = 2e5 + 5;

int n, m;
int a[N], b[N];
ll suma[N], sumb[N];

int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cin >> n >> m;
  rep(i, 1, n) cin >> a[i];
  rep(i, 1, m) cin >> b[i];
  rep(i, 1, n) suma[i] = suma[i - 1] + a[i];
  rep(i, 1, m) sumb[i] = sumb[i - 1] + b[i];
  int cnt = 0;
  for (int i = 1, j = 1; i <= n && j <= m;) {
    if (suma[i] == sumb[j])
      cnt++, i++, j++;
    else if (suma[i] < sumb[j])
      i++;
    else
      j++;
  }
  cout << n + m - cnt * 2;
  return 0;
}